The world goes through hundreds of billions of single-use coffee cups every year, and most are not recycled.That's why big coffee chains switching to paper cups is a good step, right?Well no.
A recently published study shows that paper cups can be as toxic as conventional plastic ones if they end up discarded in our natural environment.Paper cups, apparently ecological, are covered with a thin layer of plastic to prevent their contents from seeping into the paper, and this coating can emit toxins."There are chemicals that leach out of these materials," says lead author Bethanie Carney Almroth, an associate professor of environmental sciences at the University of Gothenburg in Sweden. Burger Box
When trying to evaluate the environmental impact of takeaway coffee cups, most experiments have focused on plastic lids and Styrofoam cups.Paper cups have not been studied for a long time.To fill this gap, Carney Almroth and her colleagues tested the effects of paper and plastic cups on midge larvae, which are often used in toxicity tests.The glasses were placed in warm water or sediment and allowed to leach for up to four weeks.The larvae were then kept in aquariums containing water or sediment contaminated by the paper and plastic cups.Regardless of the source of the contamination, the larvae grew less in the sediment and exposure to contaminated water also hindered their development.
Ecotoxicologists did not perform chemical analyzes to determine what substances had leached from the paper cups into the water and sediment, although Carney Almroth suspects that a mixture of chemicals caused the damage.But it is difficult to say more, since it is not known what materials are present: "All this would be much easier if companies were required to tell us what they use in their products," he proposes.
Coffee cups are made from a complex mix of synthetic materials and chemicals.Manufacturers add processing aids, heat stabilizers and other substances, many of which are known to be toxic.Although materials of plant origin are used, such as polylactic acid, derived from corn, cassava or sugar cane and used to coat paper cups, cup manufacturers often add other chemicals during processing.
Chemical analyzes can sometimes shed light on the composition of substances present in a plastic or paper cup, but even these tests cannot always identify what is there, says Jane Muncke, an environmental toxicologist by training and now managing director of the Forum. of Envases Alimentarios, a scientific communication organization based in Switzerland.The exact substances are "unknown not only to the scientists who perform these analyses, but also to the people who produce and sell the packaging."During the manufacturing of products containing plastic, unintentional chemical reactions can occur between the materials used to create new substances.
Chemicals can also be harmful because of the specific combinations in which they are used, Muncke adds, something known as "mixture toxicity," so there is little point in regulating the amounts of individual substances in glasses. clarifies, because we cannot yet be sure of the impact they will have.
Improving recycling practices would be a logical step to prevent harmful chemicals from ending up in nature, but researchers say it is best to completely phase out disposable paper cups.Most recycling centers find it difficult to separate the plastic liner from the cup paper.In the UK, for example, only a few recycling centers accept paper cups.Many cafes collect them for recycling, but having to deposit paper cups eliminates the convenience of a single-use product.Currently, only four in 100 paper cups are recycled in the UK.
Additionally, chemical leaching is not just a problem when paper cups are thrown away;may begin when using a glass.In 2019, a research group in India filled paper cups with hot water to see if plastic particles or chemicals were released."What surprised us was the amount of microplastic particles that leached into the hot water within 15 minutes," Anuja Joseph, a research fellow at the Indian Institute of Technology in Kharagpur, wrote in an email.On average, there were 25,000 particles per 100 ml cup.The researchers also found traces of harmful chemicals and heavy metals in the water and the plastic liner, respectively.
"Reusable" cups are not necessarily much better when it comes to leaching, as they are usually made of plastic;Heat and wear accelerate leaching, and acidic beverages like coffee absorb chemicals more easily.The carbon footprint of reusable plastic cups is also debatable.By some estimates, a reusable cup has to be used between 20 and 100 times to offset its greenhouse gas emissions compared to a disposable one.Blame it on the large amount of energy needed to make the reusable cup durable and the hot water needed to wash it.That said, a reusable plastic cup at least has the potential to last longer and is easier to recycle.
For Carney Almroth, reusable plastic cups are not the solution;In his opinion, fewer raw materials should be extracted and processed to make plastics, "but we also have to study the alternatives that are proposed as we move towards something more sustainable to ensure that we are not substituting one product for another," he warns.Carney Almroth is part of a coalition of scientists providing evidence to negotiations for a global plastics treaty.Negotiations will continue in Kenya in November.
Meanwhile, safer and more sustainable solutions are being sought.Some companies have baked edible cups made of waffles or cookies, or used an origami-like technique to fold paper into cup shapes.Both Carney Almroth and Muncke see the possibility for companies to use already established materials to shape a circular economy.So coffee shops could more easily replace their low-cost plastic and paper cups.
For example, glass, which keeps the drink hot for longer, its low thermal conductivity prevents the heat of the liquid from dispersing in the glass, and it is chemically inert, meaning it does not leach;Even the glaze on a ceramic glass is slightly soluble and can leach to some extent.But although glass is infinitely recyclable, its environmental footprint is greater than that of plastic.It is manufactured from natural raw materials, such as sand, which must be extracted and melted at very high temperatures.
Stainless steel, a metal commonly used for reusable water bottles, is another contender.But coffee in steel mugs cools faster than in ceramic or glass mugs, because the heat is transferred to the material and then to the palm of your hand.However, the material is more robust, making it ideal for drinks on the go.
Regardless of which material is successful, the shift away from disposable cups will require innovative business models and approaches, according to Muncke.By this he means companies finding a viable way to rent and collect reusable cups, wash them properly, ensure they are not contaminated, and put them back into circulation."The difficult thing is to change people's behavior and create all the infrastructure. And that costs a lot of money."Convenience and low cost will make disposable cups hard to beat.
Article originally published in WIRED UK.Adapted by Mauricio Serfatty Godoy.
Some studies and reports mentioned in this article:
Translated and adapted by Mauricio Serfatty Godoy
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